Angular 9 从不调用 HammerGestureConfig.buildHammer

Question

更新到 Angular 9 后，不再使用 Hammer.js。我们扩展了 Angular HammerGestureConfig像下面这样:

import {HammerGestureConfig} from '@angular/platform-browser';
import {Injectable} from '@angular/core';

@Injectable({providedIn: 'root'})
export class HammerConfig extends HammerGestureConfig {

  overrides = <any>{
    'pan': {
      direction: Hammer.DIRECTION_ALL,
      threshold: 5
    } // override default settings
  };

  buildHammer(element) {
    const recognizers = [];
    if (element.hasAttribute('data-hammer-pan')) {
      recognizers.push([Hammer.Pan]);
    }
    if (element.hasAttribute('data-hammer-pan-x')) {
      recognizers.push([Hammer.Pan, {direction: Hammer.DIRECTION_HORIZONTAL}]);
    }
    if (element.hasAttribute('data-hammer-tap')) {
      recognizers.push([Hammer.Tap]);
    }
    if (element.hasAttribute('data-hammer-pinch')) {
      recognizers.push([Hammer.Pinch]);
    }
    if (element.hasAttribute('data-hammer-rotate')) {
      recognizers.push([Hammer.Rotate]);
    }
    if (element.hasAttribute('data-hammer-press')) {
      recognizers.push([Hammer.Press]);
    }
    if (element.hasAttribute('data-hammer-swipe')) {
      recognizers.push([Hammer.Swipe]);
    }
    const hammer = new Hammer.Manager(element, {
      recognizers: recognizers,
      touchAction: 'auto'
    });
    return hammer;
  }
}

HammerConfig被添加到应用程序模块中。:

  providers: [
    {
      provide: HAMMER_GESTURE_CONFIG,
      useClass: HammerConfig
    }
  ],

据我了解的方法 buildHammer应该被调用，但它永远不会被调用。

可能是什么问题呢？

Answer 1

HammerModule需要导入到 Angular 应用模块。

  imports: [
    ...
    HammerModule
  ],
  providers: [
    {
      provide: HAMMER_GESTURE_CONFIG,
      useClass: HammerConfig
    },
    ...
  ],
  ...

ivy: make Hammer support tree-shakable. Previously, in Ivy applications, Hammer providers were included by default. With this commit, apps that want Hammer support must import HammerModule in their root module. (#32203) (de8ebbd)

https://github.com/angular/angular/blob/9.0.0/CHANGELOG.md